need help with chimney repair

[palpitating_coffee]

can i still repair loose bricks at the top of my chimney? the mortar's crumbling too. do i just replace the mortar on the chimney cap? Please help!

 

[TheClock]

I need to see what it looks like, but if it's just according to your quick explanation, I'd say, knock off the brick courses that have the crumbling side. then you can rebuild it from there